Recover Windows Product Key from non-boot drive

I boot from a master drive. I have a corrupted slave drive attached. GetDataBack allows me to retrieve files off it. Is it possible to retrieve the Windows Product Key from the slave drive? (The owner has lost the COA.)

I know there's perhaps one file I can extract from a Windows dir that was rumored to bypass activation if installed on same hardware (though found to be not true). But if I repair the drive and reinstall the OS (with maybe a dummy OEM Product Key), will reapplying that file allow me to restore the true legitimate Product Key?

The product key can be reverse engineered from the DigitalProductId found in the registry key:HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion

This registry key should be stored in the file C:\WINDOWS\system32\config\software" (no extension). I'm not sure if the registry is plaintext or hex. Looking at a .REG backup of the registry suggests a mix of the two.

Load Hive option - allows you to load the registry hive of another Windows installation. To use, put the hard drive in a working machine (must also be Windows 2000,XP or Vista) or use Windows PE (not tested, should work) and click Load Hive. Then point it to the dead Windows install. If you're using Windows Vista, Administrator rights are required for this feature. You may have to right click on the Keyfinder and run as Administrator.